This invention is directed to a silicon-containing polymer and to a process for the preparation thereof.
Various types of silicon-containing polymers are hitherto known. Among them, a silicon-containing polymer having recurring structural units represented by the following formula (a): 
wherein Ar represents an arylene group and R1 and R2 each represent a substituent such as an aryl group, an alkoxy group or an alkyl group, is excellent in resistance to heat and is studied for use as an aerospace material (J. Appl. Polym. Sci., 9, 295(1965); J. Polym. Sci., A, Polym. Chem., 32, 131(1994)).
The silicon-containing polymer having the recurring structural units represented by the above formula (a) is produced by polycondensation of hydroquinone with a di-substituted silane or dehydrogenative polymerization of quinone with di-substituted silane.
It is an object of the present invention to provide a novel silicon-containing polymer having a main chain which comprises organic groups, oxygen atoms and silicon atoms.
Another object of the present invention is to provide an industrially advantageous process for the production of a silicon-containing polymer having a main chain which comprises organic groups, oxygen atoms and silicon atoms.
In accordance with the present invention there is provided a silicon-containing polymer represented by the following general formula (1); 
wherein Ar represents an arylene group which may have a substituent, R represents a hydrocarbyl group which may have a substituent and n is a number average polymerization degree of 2-5,000.
The present invention also provides a process for the production of a silicon-containing polymer represented by the above general formula (1), characterized in that at least one compound selected from quinone and aromatic diols and at least one trihydrosilane represented by the following general formula (3): 
wherein R represents a hydrocarbyl group which may have a substituent, are subjected to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
The present invention further provides a process for the production of a silicon-containing polymer represented by the following general formula (2): 
wherein A represents an aralkylene group which may have a substituent or an alkylene group which may have a substituent, R1 and R2 each represent a hydrocarbyl group which may have a substituent but one of R1 and R2 is an aryl group and n is a number average polymerization degree of 2-5,000, characterized in that at least one diol represented by the following general formula (4):
HOxe2x80x94Axe2x80x94OHxe2x80x83xe2x80x83(4)
wherein A represents an aralkylene group which may have a substituent or an alkylene group which may have a substituent and at least one dihydrosilane represented by the following general formula (5): 
wherein R1 and R2 each represent a hydrocarbyl group which may have a substituent but one of R1 and R2 is an aryl group, are subjected to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
The present invention further provides a process for the production of a silicon-containing polymer represented by the following general formula (6): 
wherein Y represents a divalent hydrocarbyl group which may have a substituent, R3 and R4 each represent a hydrocarbyl group which may have a substituent and n is a number average polymerization degree of 2-5,000, characterized in that at least one diol represented by the following general formula (7):
HOxe2x80x94Yxe2x80x94OHxe2x80x83xe2x80x83(7)
wherein Y represents a hydrocarbyl group which may have a substituent and at least one dihydrosilane represented by the following general formula (8): 
wherein R3 and R4 each represent a hydrocarbyl group which may have a substituent, are subjected to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
In the above general formula (1), Ar represents an arylene group which may have a substituent. The arylene group has 6-18 carbon atoms, preferably 6-12 carbon atoms. The arylene group may be phenylene or naphthylene. The substituent may be a halogen atom (chlorine, bromine, iodine or fluorine), a cyano group, an alkoxy group, an aryloxy group, etc. Specific examples of the arylene group include various 1,4-phenylenes and 1,4-naphthylenes such as 1,4-phenylene, 1,4-naphthylene, 2-t-butyl-1,4-phenylene, phenyl-1,4-phenylene, 2,5-dimethyl-1,4-phenylene, 2,3,5,6-tetramethyl-1,4-phenylene, 2,5-dichloro-1,4-phenylene, 2,3,5,6-tetrachloro-1,4-phenylene and 2,3-dichloro-5,6-dicyano-1,4-phenylene.
In the above general formula (1), R represents a hydrocarbyl group. The hydrocarbyl group has 1-18 carbon atoms, preferably 1-12 carbon atoms. The hydrocarbyl group may be an alkyl group having 1-18 carbon atoms, preferably 1-12 carbon atoms, a cycloalkyl group having 4-10 carbon atoms, preferably 6-8 carbon atoms, an aryl group having 6-18 carbon atoms, preferably 6-12 carbon atoms or an aralkyl group having 7-17 carbon atoms, preferably 7-11 carbon atoms. The hydrocarbyl group may have a substituent such as a halogen atom, a cyano group, an alkoxy group or an aryloxy group. Examples of the hydrocarbyl group include phenyl, p-tolyl, m-tolyl, p-anisyl, p-chlorophenyl, p-fluorophenyl, p-trifluoromethylphenyl, p-cyanophenyl, methyl, ethyl, isopropyl, sec-butyl, hexyl and benzyl.
In the above general formula (1), n represents a number-average polymerization degree and is 2-5,000, especially 5-1,000.
The silicon-containing polymer of the above general formula (1) may be produced by subjecting at least one compound selected from quinone and aromatic diols and at least one trihydrosilane represented by the above general formula (3) to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
The quinone includes various benzoquinones and naphthoquinones. Examples of quinone include 1,4-quinones such as 1,4-benzoquinone, 1,4-naphthoquinone, 2-t-butyl-1,4-benzoquinone, phenyl-1,4-benzoquinone, 2,5-dimethyl-1,4-benzoquinone, 2,3,5,6-tetramethyl-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
The aromatic diol is not specifically limited but is preferably hydroquinone or resorcinol. Examples of hydroquinone and resorcinol include hydroquinone, methylhydroquinone, t-butylhydroquinone, chlorohydroquinone, 2-methoxyhydroquinone, phenylhydroquinone, 2,3-dimethylhydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,3,5,6-tetrachlorohydroquinone, resorcinol, 2-methylresorcinol, 4-hexylresorcinol, 5-phenylresorcinol and 1,4-dihydroxynaphthalene.
The above-mentioned trihydrosilane is not specifically limited. Examples of trihydrosilane include phenylsilane, p-tolylsilane, m-tolylsilane, p-anisylsilane, p-chlorophenylsilane, p-fluorophenylsilane, p-trifluoromethylphenylsilane, p-cyanophenylsilane, methylsilane, ethylsilane, isopropylsilane, sec-butylsilane, hexylsilane and benzylsilane.
The palladium-containing catalyst for use in the present invention may be various kinds of conventionally known catalysts. A palladium complex having a tri-substituted phosphine ligand is preferably used. The substituent may be an alkyl group having 1-12 carbon atoms, preferably 1-6 carbon atoms, a cycloalkyl group having 4-10 carbon atoms, preferably 6-8 carbon atoms, an aryl group having 6-12 carbon atoms, preferably 6-10 carbon atoms, an aralkyl group having 7-11 carbon atoms, preferably 7-9 carbon atoms. Examples of the palladium-containing catalyst include bis(triphenylphosphine)dichloropalladium, bis(triethylphosphine)dichloropalladium, bis(tricyclohexylphosphine)palladium, tetrakis(triphenylphosphine)palladium, tris(triethylphosphine)palladium, (tetramethylethylenediamine)dichloropalladium, allylpalladiumchloride dimer, bis(benzonitrile)dichloropalladium, (1,5-cyclooctadiene)dichloropalladium, tris(dibenzylideneacetone)dipalladium, bis(acetylacetonate)palladium, palladium acetate, palladium chloride and palladium black.
The molar ratio of the quinone and/or aromatic diol to the trihydrosilane is not specifically limited. From the standpoint of the molecular weight of the polymer, however, the molar ratio of the quinone and/or aromatic diol to the trihydrosilane is preferably in the range of 1:5 to 5:1, more preferably in the range of 1:2 to 2:1. The molar ratio of the trihydrosilane to the palladium of the palladium-containing catalyst is not limited, either. For reasons of yield, however, the molar ratio of the trihydrosilane to the palladium of the palladium-containing catalyst is preferably in the range of 10,000:1 to 2:1, more preferably in the range of 2,000:1 to 5:1.
The reaction in the present invention may be carried out without using a solvent when one of the raw materials is a liquid. Generally, however, a solvent such as a hydrocarbon solvent (e.g. benzene, toluene or hexane), an ether solvent (e.g. diethyl ether, tetrahydrofuran (THF) or dioxane), a halogen-containing solvent (e.g. methylene chloride or chloroform) may be used. The reaction temperature is not specifically limited, either. For reasons of reactivity and stability of the raw materials, the reaction temperature is in the range of 0-150xc2x0 C., preferably 20-120xc2x0 C.
The silicon-containing polymer thus obtained is a polymer in which structural units of the following general formula (9):
"Parenopenst"Oxe2x80x94Arxe2x80x94O"Parenclosest"xe2x80x83xe2x80x83(9)
are alternately linked to structural units of the following general formula (10): 
The plurality of Ar contained in the polymer may be the same or different. The plurality of R contained in the polymer may be also the same or different.
In the above general formula (2), A represents an aralkylene group, an alkylene group or a cycloalkylene group. The aralkylene group may include a phenylene alkylene group, a phenylene dialkylene group, a naphthylene alkylene group or a naphthylene dialkylene group and has 6-18 carbon atoms, preferably 6-12 carbon atoms. The alkylene group may be alkylene having 1-18 carbon atoms, preferably 2-12 carbon atoms. The cycloalkylene group may be cycloalkylene having 4-10 carbon atoms, preferably 6-8 carbon atoms. The substituent may be a halogen atom (chlorine, bromine, iodine or fluorine), a cyano group, an alkoxy group, an aryloxy group, etc. Specific examples of the divalent group A include ethylene, 1,3-propylene, 1,4-butylene, 1,3-butylene, 1,4-cyclohexylene, phenyl-1,2-ethylene, dimethyl-2,3-butylene, xcex1,xcex1xe2x80x2-p-xylylene, xcex1,xcex1xe2x80x2-m-xylylene and naphthylene-1,3-dimethylene.
In the above general formula (2), R1 and R2 each represent a hydrocarbyl group but one of R1 and R2 is an aryl group. The hydrocarbyl group may include an alkyl group having 1-18 carbon atoms, preferably 1-12 carbon atoms, a cycloalkyl group having 4-10 carbon atoms, preferably 6-8 carbon atoms, an aryl group having 6-18 carbon atoms, preferably 6-12 carbon atoms or an aralkyl group having 7-17 carbon atoms, preferably 7-11 carbon atoms. The hydrocarbyl group may have a substituent such as a halogen atom, a cyano group, an alkoxy group or aryloxy group. Examples of the hydrocarbyl group include methyl, ethyl, propyl, butyl, hexyl, dodecyl, cyclohexyl, phenyl, naphthyl, benzyl, tolyl, anisyl or trifluoromethylphenyl.
In the above general formula (2), n represents a number average polymerization degree and is 2-5,000, especially 5-1,000.
Specific examples of the silicon-containing polymer represented by the general formula (2) include: poly[xcex1,xcex1xe2x80x2-p-xylylenedioxy(phenylmethylsilylene], poly[xcex1,xcex1xe2x80x2-p-xylylenedioxy(diphenylsilylene], poly[xcex1,xcex1xe2x80x2-m-xylylenedioxy(diphenylsilylene], poly[1,2-ethylenedioxy(naphthylmethylsilylene], poly[1,4-butylenedioxy(phenylmethylsilylene] and poly[1-phenyl-1,2-ethylenedioxy(diphenylsilylene].
The silicon-containing polymer represented by the above general formula (2) may be produced by subjecting at least one diol represented by the above general formula (4) and at least one dihydrosilane represented by the above general formula (5) to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
Examples of the diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,4-cyclohexanediol, phenyl-1,2-ethanediol, dimethyl-2,3-butanediol, xcex1,xcex1xe2x80x2-p-xylylenediol and xcex1,xcex1xe2x80x2-m-xylylenediol.
Examples of the dihydrosilane include phenylmethylsilane, naphthylmethylsilane, phenylbenzylsilane, tolylmethylsilane, anisylmethylsilane, trifluoromethylphenylmethylsilane, diphenylsilane, ditolylsilane, dianisylsilane, bis(trifluoromethylphenyl)silane, dinaphthylsilane and phenylethylsilane.
As the palladium-containing catalyst, there may be used various palladium-containing catalysts described above with reference to the silicon-containing polymer of the general formula (1).
The molar ratio of the diol to the dihydrosilane is not specifically limited but is preferably in the range of 1:5 to 5:1, more preferably in the range of 1:2 to 2:1. The molar ratio of the dihydrosilane to the palladium of the palladium-containing catalyst is not limited, either. For reasons of yield, however, the molar ratio of the dihydrosilane to the palladium of the palladium-containing catalyst is preferably in the range of 10,000:1 to 2:1, more preferably in the range of 2,000:1 to 5:1.
The reaction in the present invention may be carried out without using a solvent when one of the raw materials is a liquid. Generally, however, a solvent such as a hydrocarbon solvent (e.g. benzene, toluene or hexane), an ether solvent (e.g. diethyl ether, THF or dioxane), a halogen-containing solvent (e.g. methylene chloride or chloroform) may be used. The reaction temperature is not specifically limited, either. For reasons of reactivity and stability of the raw materials, the reaction temperature is in the range of 0-150xc2x0 C., preferably 20-120xc2x0 C.
The present invention comprises a process of producing a silicon-containing polymer represented by the above general formula (6). This process uses at least one diol represented by the above general formula (7) as the starting material diol.
In the general formula (7), Y represents a divalent hydrocarbyl group. The hydrocarbyl group has 1-18 carbon atoms, preferably 1-12 carbon atoms. The hydrocarbyl group may be an alkylene group having 1-18 carbon atoms, preferably 1-12 carbon atoms, a cycloalkylene group having 4-10 carbon atoms, preferably 6-8 carbon atoms, an arylene group having 6-18 carbon atoms, preferably 6-12 carbon atoms or an aralkylene group having 7-17 carbon atoms, preferably 7-11 carbon atoms. The hydrocarbyl group may have a substituent such as a halogen atom, a cyano group, an alkoxy group or aryloxy group. Examples of the hydrocarbyl group include ethylene, 1,3-propylene, 1,4-butylene, 1,3-butylene, 1,4-cyclohexylene, phenyl-1,2-ethylene, dimethyl-2,3-butylene, xcex1,xcex1xe2x80x2-p-xylylene, xcex1,xcex1xe2x80x2-m-xylylene, 1,4-phenylene, methyl-1,4-phenylene, t-butyl-1,4-phenylene, chloro-1,4-phenylene, 2-methoxy-1,4-phenylene, phenyl-1,4-phenylene, 2,3-dimethyl-1,4-phenylene, 2,3,5,6-tetramethylene-1,4-phenylene, 2,3,5,6-tetrachloro-1,4-phenylene, 1,3-phenylene, 2-methyl-,1,3-phenylene, 4-hexyl-1,3-phenylene, 5-phenyl-1,3-phenylene and 1,4-naphthylene.
The silicon-containing polymer of the above general formula (6) may be produced by subjecting at least one compound selected from those diols represented by the above general formula (7) and at least one compound selected from those dihydrosilane represented by the above general formula (8) to dehydrogenative polymerization in the presence of a palladium-containing catalyst.
Examples of the diol represented by the above general formula (7) include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,4-cyclohexanediol, phenyl-1,2-ethanediol, dimethyl-2,3-butanediol, xcex1,xcex1xe2x80x2-p-xylylenediol, xcex1,xcex1xe2x80x2-m-xylylenediol, hydroquinone, methylhydroquinone, t-butylhydroquinone, chlorohydroquinone, 2-methoxyhydroquinone, phenylhydroquinone, 2,3-dimethylhydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,3,5,6-tetrachlorohydroquinone, resorcinol, 2-methylresorcinol, 5-phenylresorcinol and 1,4-dihydroxynaphthalene.
Examples of the dihydrosilane represented by the above general formula (8) include those described with reference to the dihydrosilane of the above general formula (5) and, additionally, dimethylsilane, propylmethylsilane, butylmethylsilane, hexylmethylsilane, dodecylmethylsilane, dibutylsilane, dihexylsilane, dicyclohexylsilane, dibenzylsilane and dibenzylethylsilane.
The production of the silicon-containing polymer of the above general formula (6) may be carried out in the same manner as that of the silicon-containing polymer of the above general formula (2).